What can the electricity produced be used for?
The simplest solution is to supply the common needs: lift, ventilation, lighting or pumps.
The electricity may also be shared between several occupants through collective self-consumption. An energy community may bring together several participants or buildings.
These models involve different meters, agreements and responsibilities.
Why start with the roof?
One must check the state of the covering, its load-bearing capacity, the shading, the access points and the existing equipment.
Installing panels on a roof that will have to be renovated a few years later may entail a costly removal. The project must be coordinated with the works plan.
One must also determine whether the roof is entirely common and whether rights of enjoyment limit the surface area available.
Who owns the installation?
The syndicate may carry the project, but other structures may be proposed. This question influences the invoices, subsidies, insurance, maintenance and benefits.
Where a third party wishes to finance or operate the installation, one must characterise the right granted over the roof. A service contract does not have the same effects as a durable provision or a real right.
The creation of a real right over a common part may be validly decided only by a majority of the members of the syndicate representing at least three quarters of the votes. The alienation of a common part whose preservation is necessary to respect the intended use of the building requires unanimity. The structure must therefore be characterised before the convocation, and not discussed in the meeting.
How does collective self-consumption work?
In a residence, several users behind the same connection point may share a local production on the low-voltage network of the same operator.
Two agreements are necessary: one with the network operator, the other between the participants. Participation remains voluntary and at least one participant must own the installation.
Each participant keeps their supply contract for the periods when the production is not sufficient.
What must the file presented to the general meeting include?
The file distinguishes panels, roof, connection, protections, meters, maintenance, insurance and management.
The production assumptions must be compared with the consumption profiles. An annual estimate is not enough: the value depends on the electricity consumed at the moment it is produced.
One must also anticipate the sale of a lot, the arrival of a participant and the repairs. Where an installation has been financed by certain co-owners and its use is reserved to them, a new user may have to pay their share of the cost, assessed as of the date of their entry.
The works fund may contribute to financing the collective part of the project if the general meeting decides on its allocation.
Which majority must be reached?
Installations for the production and storage of renewable energy in the common parts fall to a majority of the votes of all the co-owners. A new general meeting may decide under the conditions provided for by law if this majority is not reached.
A structure conferring a right on a third party may fall under a different majority and must be characterised before the convocation.
What role do the 2026 subsidies play?
Klimabonus 2026 provides, subject to final publication, subsidies for certain installations operated in self-consumption or in an energy community, as well as for certain batteries.
Pre-financing allows, under conditions, the subsidy to be deducted from the invoice by an installer entered in the register of installers admitted to the procedure. The request is submitted by the installer, in the name of the beneficiary, on the basis of a mandate. In a co-owned building, the beneficiary may be either the syndic or a co-owner designated by the general meeting: this designation must appear on the agenda.
The timetable of the subsidies for photovoltaics and storage is not that of the other technical installations. As of 6 August 2026, subject to the final publication of the texts, the invoices must be issued between 4 January 2026 and 31 December 2029. The deadline is extended to 31 December 2031 where the installation was ordered by 31 December 2029 at the latest. The request must be submitted by 31 December 2031 at the latest.
Reference texts
- Law of 1 August 2007 on the organisation of the electricity market
- Klima-Agence, collective self-consumption
- Klima-Agence, solar electricity
- Guichet.lu, Klimabonus 2026
- Guichet.lu, pre-financing
- Law of 16 May 1975 establishing the statute of co-ownership of built property (Mémorial A No 28 of 23 May 1975), in particular Articles 13, 16, 17 and 18 — point b) of Article 16 (works affecting the common parts or the external appearance) resulting from the Law of 22 April 1985 (Mémorial A No 22 of 9 May 1985), points e), f) and g) of the same Article (production and storage of energy from renewable sources) and point c) of Article 17 resulting from the Law of 30 June 2022 (Mémorial A No 347 of 11 July 2022)